1. Field of the Invention
The invention relates to a method of manufacturing liquid crystal displays.
2. Description of the Related Art
Refer to FIG. 1, a flow chart of a conventional method of manufacturing liquid crystal displays (LCDs) is illustrated. In step 11, a panel assembly structure is provided. For example, in the One Drop Fill (ODF) process, the panel assembly structure includes an upper substrate, a lower substrate, several sealants and liquid crystals. The upper substrate and the lower substrate are disposed parallel to each other. The sealants connect the inner surfaces of the first substrate and the second substrate. Liquid crystals are filled between the upper substrate and the lower substrate, and surrounded by the corresponding sealant. The upper substrate includes several color filter (CF) substrates. The lower substrate includes several thin film transistor (TFT) substrates corresponding to the CF substrates, respectively. Each CF substrate, the corresponding TFT substrate, the corresponding sealant and the corresponding liquid crystals are combined to form a liquid crystal display (LCD) panel. In another conventional liquid crystal injection process, each CF substrate, the corresponding TFT substrate and the corresponding sealant are combined to form a panel to be filled with liquid crystals.
Next, in step 12, the upper substrate and the lower substrate are cut by using a wheel cutter, for separating the LCD panels or the panels ready to be filled with liquid crystals. Meanwhile, in the liquid crystal injection process, liquid crystals are injected into each panel ready to be filled with liquid crystals through the liquid crystal injection opening of the corresponding sealant. After the liquid crystals have been injected, the liquid crystal injection openings are sealed and closed. The LCD panels manufactured by the liquid crystal injection process is formed completely in this step.
Then, in step 13, the TFT substrate of each LCD panel is ground and beveled by using a grinding wheel. The grinding wheel mainly grinds two edges of both Gate-driver side and Data-driver side of each TFT substrate that outer leads extend to. The grinding wheel also bevels partially the corners of each TFT substrate. As a result, sharp glass edges are avoided, so that, for example, connecting between a chip in a chip on glass (COG) process and an outer circuit (e.g., a driving PCB) is no more affected by such sharp edges, particularly, in a step of electrically connecting a PCB to the TFT substrate via a flexible circuit board (FPC). Alternatively, a tape automatic bonding (TAB) process is no more affected by such sharp edges, particularly, in a step of electrically connecting a package with a IC chip (also known as a tape carrier package, TCP) to the outer leads through a tape automatic bonding (TAB) process. This grinding and/or beveling process is useful especially because when a flexible circuit board (FPC) or a TCP is electrically connected to the outer leads, the flexible circuit board or the tape is easily damaged by the sharp edges or sharp corners of the TFT substrate, resulting in a decrease in the yield rate of the LCD panels.
In step 14, because many particles, powders or foreign matters are generated in step of grinding and beveling the TFT substrate by using a grinding wheel, each LCD panel is cleaned by water and then scraped to be dry. As a result, the LCD panels are kept clean for the next step. Afterward, in step 15, an upper polarizer and a lower polarizer are adhered correspondingly on outer surfaces of the CF substrate and the TFT substrate in each LCD panel. For example, a light transmission axis of the upper polarizer is perpendicular to a light transmission axis of the lower polarizer. Subsequently, in step 16, a test card is electrically connected to the outer leads of each LCD panel one by one, for inputting test signals. The image quality of each LCD panel is observed by an operator when the LCD panel is under light-emission. Usually each LCD panel is loaded/unloaded on a testing machine one by one by using a robot arm. Then, the test card is electrically connected to the outer leads of the LCD panel on the testing machine for inputting the test signals. The image quality of each LCD panel is preferably observed by the operator when the LCD panel is under light-emission, for singling out defect LCD panels to proceed a re-work process. The qualified LCD panels are continuously sent to the next process station for proceeding the next step, e.g., in step 17, a COG process or a TAB process is proceeded on each LCD panel. For example, a chip is electrically connected to the outer leads through an anisotropic conductive film (ACF) in the COG step. Then, the outer leads are electrically connected to the outer circuit, a driving PCB, through the flexible circuit board (FPC). For another example, the TCP is electrically connected to the outer leads through the ACF in the TAB step, and the PCB is electrically connected to a package through the ACF. As a result, the PCB is electrically connected to the outer leads through the TCP package. Afterward, in step 18, the LCD panel and a backlight module are assembled to form a completed LCD.
However, conventionally, the TFT substrate is ground and beveled in step 13 by using a grinding wheel. As a result, many particles, powders or foreign matters are generated. Therefore, each LCD panel need to be cleaned by water and then is scraped dry in step 14. The manufacturing steps are redundancy and complicated. The cost is raised for purchasing equipment, such as a grinding wheel machine, a cleaning machine and a scraping machine. When the particles, powders or foreign matters are still not cleaned, the LCD panels easily have defects due to the adhesion of such particles, powders or foreign matters.
Moreover, when the LCD panel is not scraped dry in step 14, the polarizers cannot be adhered well in step 15. Further, a Newton ring or a water mark occurs because the water remains on the outer surface of the LCD panel. As a result, the image quality of the LCD is affected.
Furthermore, when the panel assembly structure is cut, e.g., into 502 small-size (for example, 1.2 inch, that is, about 620 mm*750 mm) LCD panels, each LCD panel is attached with polarizers and is tested by the test card. In other words, 502 polarizers are adhered in step 15, and the automatically loaded/unloaded process is proceeded 502 times in step 16 to test all the LCD panels. As a result, it is very time-consuming to adhere polarizers and to test all the LCD panels 502 times. The manufacturing process of the LCD is inefficient and uneconomic.